1. Field of the Invention
The present invention relates to an anthracene derivative compound and an organic light-emitting device (OLED) comprising the same. More specifically, the present invention relates to an anthracene derivative compound that has good electrical characteristics, and when applied to an OLED, can provide an excellent driving voltage, efficiency, and color purity.
2. Description of the Related Art
OLEDs are active emission display devices that emit light by recombination of electrons and holes in a thin layer (hereinafter referred to as “organic layer”) formed of a fluorescent or phosphorescent organic compound when a current is supplied to the organic layer. The OLEDs have advantages such as lightness, simple constitutional elements, easy manufacturing process, superior image quality, and wide viewing angle. In addition, the OLEDs can advantageously create dynamic images, achieve high color purity, and have electrical properties suitable for portable electronic equipment due to low power consumption and low driving voltage.
Eastman Kodak Co. has developed an OLED with a multi-layered structure comprising an aluminum quinolinol complex layer and a triphenylamine derivative layer (U.S. Pat. No. 4,885,211), and an OLED comprising an organic light-emitting layer formed of a low molecular weight material capable of emitting light in a broad wavelength range from UV to infrared light (U.S. Pat. No. 5,151,629).
Light-emitting devices (LEDs) are self-emitting devices that have advantages such as a wide viewing angle, good contrast, and a rapid response time. LEDs are classified into inorganic light-emitting devices, which comprise an emitting layer formed of an inorganic compound, and OLEDs, which comprise an emitting layer formed of an organic compound. OLEDs display better brightness, driving voltage, and response speed characteristics and can produce polychromatic light, compared to inorganic light-emitting devices, and thus, extensive research into OLEDs has been conducted.
Generally, OLEDs have a stacked structure of an anode, an organic light-emitting layer, and a cathode. OLEDs may also have various structures such as anode/hole injection layer/hole transport layer/emitting layer/electron transport layer/electron injection layer/cathode or anode/hole injection layer/hole transport layer/emitting layer/hole blocking layer/electron transport layer/electron injection layer/cathode.
Materials used for OLEDs can be divided into vacuum-depositable materials and solution-coatable materials according to the organic layer manufacturing process. Vacuum-depositable materials advantageously have a vapor pressure of 10−6 torr or more at 500° C. or less, and may be low molecular weight materials having a molecular weight of 1,200 atomic mass units (amu) or less. Solution-coatable materials advantageously have solubility sufficient to form solutions, and generally comprise an aromatic or heterocyclic ring.
When manufacturing OLEDs using a vacuum deposition process, manufacturing costs may increase due to the use of a vacuum system, and it may be difficult to manufacture high-resolution pixels for natural color displays using a shadow mask. On the other hand, when manufacturing OLEDs using a solution coating process, such as inkjet printing, screen printing, spin coating, or the like, the manufacturing process is simple, manufacturing costs are low, and a relatively high resolution can be achieved compared to when using a shadow mask.
However, when using solution-coatable materials, the performance (for example, thermal stability, color purity, or the like) of light-emitting molecules is lowered compared to when using vacuum-depositable materials. Even though the light-emitting molecules of the solution-coatable materials have good performance, they provide problems when formed into an organic layer. For example, the materials gradually undergo crystallization and these crystals grow into a size that corresponds to a wavelength in the visible light regime, and thus, the grown crystals scatter visible light, thereby causing turbidity. In addition, defects such as pinholes, and the like may be formed in the organic layer, thereby causing device degradation.
Japanese Patent Laid-Open Publication No. 1999-003782 discloses a 2-naphthyl-substituted anthracene compound that can be used in an emitting layer or a hole injection layer. However, OLEDs comprising the anthracene compound are unsatisfactory in terms of driving voltage, brightness, efficiency, and color purity characteristics, and thus, there is room for improvement in conventional OLEDs.